Year	Percent
1991	34.164
1992	34.208
1993	33.927
1994	33.71
1995	42.604
1996	42.909
1997	42.497
1998	42.674
1999	43.695
2000	34.177
2001	24.124
2002	22.16
2003	21.656
2004	21.833
2005	22.597
2006	22.035
2007	21.356
2008	19.975
2009	19.514
2010	18.51
2011	19.633
2012	18.932
2013	18.482
2014	18.971
2015	18.749
2016	17.856
2017	17.672
2018	17.629
2019	17.583
2020	17.539
2021	17.496
2022	17.453